Mining pit prop adjusting device

ABSTRACT

A control system for adjusting the angular disposition of pit props of a traveling mine-roof support system comprising a command pendulum-type switch which has a rockable housing in which is a plumb-bob from which depends a swinging element. When the plumb-bob rocks to a position for measuring the angle of incidence, actuating means is activated for accordingly moving the switch housing and movement of the latter operates to emit signals to switching devices carried by the individual pit props for determining the correct angular disposition thereof in accordance with that of the command switch.

United States Patent Rieschel et al.

[ Feb. 1, 1972 MINING PIT PROP ADJUSTING DEVICE Hans Rieschel, Miltenberg; Oskar Jacobi, Blankenstein, both of Germany Inventors:

Bergwerksverband Gmbll, Essen, Germany Filed: Nov. 26, 1969 Appl. No.: 880,062

Assignee:

Foreign Application Priority Data Nov. 26, l968 Germany ..P l8 10 869.5

US. Cl ..9l/l89,6l/ D,9l/l MP,

91/461 Int. Cl ..Fl5b 11/16 Field of Search ..6l/45 D; 299/31, 33, ll;

References Cited UNITED STATES PATENTS 3,437,010 4/1969 Jacobi et al. ..,.6l/45 D l2/l969 Jacobi ..6l/45 D Primary ExaminerDennis L. Taylor Att0rneyMalcolm W. Fraser [5 7] ABSTRACT A control system for adjusting the angular disposition of pit props of a traveling mine-roof support system comprising a command pendulum-type switch which has a rockable housing in which is a plumb-bob from which depends a swinging element. When the plumb-bob rocks to a position for measuring the angle of incidence, actuating means is activated for accordingly moving the switch housing and movement of the latter operates to emit signals to switching devices carried by the individual pit props for determining the correct angular disposition thereof in accordance with that of the command switch.

7 Claims, l2 Drawing Figures PATENTEB FEB H972 3.638.531

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MINING PIT PROP ADJUSTING DEVICE BACKGROUND OF THE INVENTION The invention relates to a control system for units of a travelling mine roof support system, the props of which are maintained in their ideal position with the aid of corrective devices, for the control of the corrective cylinders there being provided pendulum-type switches associated with the roof support system, in which switches the ideal value for the props can be set,

Control systems of this type have their basis in the effect of a pendulum suspended on one prop of the mine roof support unit, the pendulum being able to swing in only one plane and therefore in the said plane reproducing the direction of the true vertical. The direction indicated by the pendulum includes a certain angle with the axis of the prop, which angle constitutes the value at one instant of a controlled condition or variable, the ideal value of which is the position prescribed for the prop, most often the attitude of the prop perpendicular to the geological stratification. The controlled condition appertains to a controller in which the pendulum-type switch forms the measuring device, and one or more corrective devices form the correcting elements for influencing the controlled condition.

Control systems of this type make it possible to maintain the position of the prop axis independent of disturbance quantities, so that the prop is able to develop its maximum supporting capacity in all phases of operation.

Whereas already known control systems of this type still function with sensors or electrical contacts, control systems not yet part of the state of the art most frequently employ as the auxiliary medium the compressed air which is generally available in mining. As experience shows, as many signals as may be required can be produced and passed on, and any danger of explosion is eliminated.

The regulators forming the constituent of the control are provided with theoretical value adjusters. In this way it is possible, with changing strut inclinations by means of new adjustment of the theoretical value to influence the pendulum switches so that the position of the strut axis may be adapted at the time to the given new conditions, i.e., given through the change in the inclination. It is, however, a disadvantage that previously the new theoretical value must be adjusted manually. For this, attendants or operators are necessarywhich is contrary to the idea of automatization, which is to be accomplished with the controls.

SUMMARY OF THE INVENTION The technical problem serving as basis for the invention is to construct a control in such manner that the theoretical value of the pendulum switches employed is adjusted automatically according to the particular strut inclination in the area of the pertaining constructional unit.

According to the invention, the solution of this problem takes place through a guide pendulum switch with a plumbline measuring the strut inclination and a switch element swinging synchronously with the plumbline for the adjustment of a switch member which corresponding to its adjustment at the time connects a signal channel from a plurality of signal channels with a source for a control medium. In this way it is possible to produce adjusting signals for the adjustment of a theoretical value setter of one or more of the pendulum switches.

With the control according to the invention, a qualitative signal is produced automatically by the guide pendulum switch, which sets the theoretical value of one or more switches according to the strut inclination. Thereon rests on the one hand, the rationalization effect occurring through the elimination of the attendant personnel required previously for the setting of the theoretical value setter on the construction pendulum switches. On the other hand, however, the increase in the accuracy of the theoretical value setting as well as the reaction speed of the control with which the latter may react upon the change in the inclination are achieved. In this manner there results an appreciable improvement in the accuracy, because the struts adapt themselves directly to the altered geological conditions and thereby always develop their maximum bearing strength.

Generally regarded, it is sufficient that the guide pendulum switch is fixed to a carrier laid on the horizontal abutment which may reproduce with sufficient accuracy an average value of the inclination in direction of feed. With this carrier, it may be a question of a sectionof the strut feed means whose length is indicated by the spacing of the construction pendulum switch controlled by the guide pendulum switch.

The adjustment of the switch member takes place suitably by means of signals which consist of impulses of a pressure medium, which is usually compressed air.

For this purpose it is provided that in the guide pendulum switch a switch element moves synchronously with the plumbline in a switch housing which is subjected constantly to pressure fluid, and swings in front of two signal apertures. In this way the passage of control medium is released through the one or the other of the signal apertures, in order to produce setting signals for a drive corresponding to the deviations of the strut inclination from the plumbline, or to lock both signal apertures, whereby the drive serves for the adjustment of the switch member.

This drive consists suitably of. a thrust piston drive for the horizontal swing of the guide pendulum switch housing, whereby then the switch member is built into the pivotal axis of this housing.

The switch member may consist of a hollow shaft with several radial bores staggered at spacings arranged on its circumference, said radial bores being connected with signal channels leading to the theoretical value adjusters or setters. The hollow shaft surrounds a rigid pin or journal which possesses individual feed or inlet bores taking effect for each radial bore of the hollow shaft, whereby all feed bores are attached to the source of pressure fluid.

In order to make use of the advantages of an auxiliary control medium in the shape of a pressure medium, particularly in form of the ordinary compressed air for the entire control, it is advisable to provide the pendulum switch with a switch housing which is constantly under the pressure of a control medium, and in which synchronously with the pendulum switch plumbline, a switch element swings in front of two pairs of signal apertures and thereby releases the passage of pressure fluid through the one or the other of the signal channels in order thereby to produce setting signals for the aligning cylinder corresponding with the deviations measured by the plumbline from the standard, or to lock both signal channels at standard sizes in agreement with the theoretical value. This assumes that a special theoretical value setter is disposed in the construction pendulum switches. This theoretical value setter consists in principle of a plurality of pairs of signal apertures, which are connected pairwise each with one of the signal channels, whereby the apertures of several signal channels combined pairwise are arranged offset to the height and/or the side in reference to the switch element.

In general the signals must be amplified, because the aligning devices as a rule consist of aligning cylinders which are subjected to high pressure. The amplification of the signals takes place previously in principle with the help of diaphragm amplifiers of diaphragm piston engines. Then care must be taken that the amplifiers are not suddenly without pressure if the guide pendulum switch carries out a change on the theoretical value setter of the construction pendulum switch.

This occurs in this way that the parts of the signal channels lying behind the controlling device through the switch element of the construction pendulum switch are provided with check or back pressure valves, which close automatically in direction to the switch element and that in addition the chambers behind the check or back pressure valve are connected through throttles with the atmosphere.

DESCRIPTION OF THE DRAWING The individual features of the invention are explained on the basis of the drawings.

In the drawings:

FIG. 1 shows in elevation a guide pendulum switch according to the invention with the carrier pertaining thereto disposed on the horizontal abutment.

FIG. 2 is a lateral view of the switch according to FIG. 1.

FIG. 3 is a rear view of the switch according to FIG. 1.

FIG. 4 is a diagrammatical illustration according to FIG. 1 showing the action of the guide pendulum switch upon a change in the inclination of the horizontal abutment.

FIG. 5 shows diagrammatically the switch member, the signal channels connected therewith and a construction pendulum switch fixed on a mine prop.

FIG. 6 shows a section through the theoretical value setter of the construction pendulum switch according to the line VIVI of FIG. 5.

FIG. 7, 7a, 7b, 7c and 7d shows five sections through the switch member according to FIG. 5 taken on the lines VII, VIIa, Vllb, Vllc and WM, respectively, and

FIG. 8 shows diagrammatically a circuit diagram of a regulator, in which a pendulum switch forms the measuring device for the standard size and a hydraulic thrust piston drive the setting member for the influencing of the standard size.

DESCRIPTION OF THE PREFERRED EMBODIMENT For the better understanding of the invention, it is first necessary to explain the principle of the regulator according to FIG. 8, which in itself is not the object of the invention, however, in the different pendulum switches, which the controlling device according to the invention utilizes, is used in the manner to be described later.

The regulator operates with a control medium under pressure, which is usually compressed air that is available in the mine or excavation. The compressed air passes first from the delivery pipe 130 into a pressure reducing valve 131. There it is brought to a pressure so low, that it may constantly be supplied through two feed pipes 101 or 102, respectively branching out of a main conduit 132 to a switch housing 133. From two delivery channels 134 and 135 compressed air flows out constantly. This control compressed air passes to the inner chamber 103 of the switch housing 133.

In this switch housing a plumbline, (not shown) moves and it consists of a mass which is connected with a flat switch element 136. This switch element may swing synchronously with the mass of the plumbline in direction of the two arrows indicated on the switch element 136.

Opposite the feed channels 134 and 135 are located outlet channels 138 or 139, respectively, from which lead outlet tubes 104 and 105. In addition, the inner chamber 103 of the switch housing 133 has also a passage 140 open to the outside. The two outlet tubes 104 or 105, respectively terminate each at an amplifier 141, in order to amplify the incoming signals. Each amplifier has a diaphragm piston which actuates through a rod a two-way valve 106 106a Each valve is tensioned by a spring 142 in a nominal position indicated in FIG. 8. In the position indicated at 106b at the conduits 130a and 130b, respectively are blocked.

In the position 106a of each valve, counterpressure air may pass from the conduit 130:: to a servomotor 115 in the form of an operating cylinder which on its part actuates a three-way valve 108, so that pressure fluid flow from a conduit 150 to a position 108:: of the two-way valve to a piston chamber 107a or to a piston chamber 10712, or to a position 108b from the mentioned chambers to the storage tank 151 through conduits 152 or 153, respectively.

Upon swinging out of the plumbline, the switch element 136 controls the connection between the inlet and outlet channels 134 or 138. respectively, whereby compressed air may pass from the conduit I32 into the conduit 104 to the amplifier I41 shown at the left. Thereby the diaphragm of the amplifier 141 is deflected and produces the position 106a of the two-way valve 106. The servomotor receives pressure from the conduit a and shifts thereby the two-way slide member 108 into the position 108a, so that out of the conduit I50 pressure fluid may pass into the piston chamber 107a of the operating cylinder. I

As now at the same time the two-way valve 108 in the righthand part of FIG. 8 remains in the position 108b, pressure means may pass from the piston chamber 107b to the tank 151.

Under these circumstances the piston rod 123 enters the operating cylinder 121. Retraction of the piston rod 123 from the operating cylinder 121 is caused by the reverse deflection of the switch element 136.

The control according to the invention consists of a guide pendulum switch 1, which fundamentally operates according to the foregoing principle explained on the basis of FIG. 8, so that in FIGS. 1 to 7d, the control members insofar in agreement with FIG. 8 are either omitted or indicated diagrammatically.

The guide pendulum switch is mounted on a carrier 3, disposed on a horizontal abutment, for example, on a feed or conveyor chute or trough. On the latter is fixedly arranged a fastening 2. On the post 2 is fastened an arm 4 whose offset end serves as a support for the swingable fastening of a cylinder 5. The cylinder 5 serves as drive for the adjustment of a switch member, which will be explained more in detail below.

A piston rod 6 of the cylinder 5 is connected with a switch housing, which corresponds to the housing I33 of FIG. 8. This switch housing may swing about a shaft 7 upon movement of the piston rod 6 within the cylinder 5.

If it is assumed that in FIGS. 1 to 3 the carrier 3 is positioned horizontally, then the plumbline direction L indicated by the pendulum 8a and the normal coincide with the plane of the carrier 3 or of the horizontal line, respectively. In FIG. 4 are shown the changes which occur if the abutment horizontal line inclines about the angle a.

Before the condition according to FIG. 4 is attained, first the pendulum migrates out of its middle position shown in FIG. 3. The pendulum 8a rocks also the switch element 136', (FIG. 3) so that the amplifier 141 is actuated, which corresponds to the amplifier 141 shown to the left in FIG. 8. To the contrary, the amplifier I41" remains uninfluenccd, which corresponds to the amplifier 141, which is shown to the right in FIG. 8. In view thereof, now the pressure fluid flows through the conduit I52, and the chamber 107a of the cylinder 5, while the chamber l07b is exhausted of pressure fluid through the conduit 153'.

The piston rod 6 thus moves into the cylinder 5, and rocks the switch housing 1 which corresponds to the housing 133, so that the center axis S of the housing 1 (FIG. 4) is in agreement with the plumbline direction L and subsequently with the axis A incorporates the angle a.

The center axis S of the switch housing 1 coincides at the beginning of a horizontal swing of the carrier 3 on account of a change in the inclination about the angle a with the axis A, that is, the switch housing joins in the movement of the carrier 3. On account of the control through the switch element 136', however, the switch housing 1 and therewith its axis S is dis placed in the plumbline direction.

On the rear side of the switch housing 1, shown in FIG. 5 on an enlarged scale, however, broken away, is positioned a hollow shaft 1', which is constructed in one piece with the rear wall of the switch housing. The hollow shaft rotates upon the horizontal mounting of the switch housing I under the influence of the drive, in the form of the cylinder 5 with its piston rod 6, i.e., about the axis of the fixed shaft 7, as shown the hollow shaft 1' rotates about the shaft attachment 10 which is formed in one piece with the shaft 7. The shaft attachment 10 has a bore 11, which is supplied with compressed air of substantially constant pressure. The compresscd air is supplied through a bore 12 to the rear wall of the housing 1 by an annular groove 13.

At determined axial distances on the shaft are arranged radial bores 14 to 18 (FIGS. 7 to 7d), which go out from the axial bore 11 and carry through the shaft attachment 10. In the same radial plane as the bores 14 to 18 are located bores in the hollow shaft 1', which are provided with connections 19 to 23.

The described arrangement of the hollow shaft 1' and the shaft attachment 10 form with the bores and connections a switch member. This switch member in the guide pendulum switch, in accordance with the foregoing explanations is adjusted or displaced through the switch element 136' swinging synchronously with the plumbline L. Its particular position is measured digitally by the connections 19 to 23.

The five individual conduits 19 to 23 shown in FIG. 5 are combined into a cable 24. The cable 24 leads to several pendulum switches correlated with the construction, not shown. One of these pendulum switches is shown to the left in FIG. 5. Its switch housing 133" is arranged fixedly on a hydraulic mine prop indicated at 29. In view thereof, each horizontal swing of the prop 29 leads to a corresponding horizontal swing of the switch housing 133".

In the switch housing 133" is suspended the mass 30 of a plumbline, as a pendulum, on which is located a fiat switch element 136". In view thereof, the mass 136" swings synchronously with the mass 30 of the plumbline.

The pneumatic cable 24 comprising the individual leads contains pressure fluid channels 26 for the pendulum switch on the prop 29. The pendulum switch housing 133" has corresponding connections 19 to 23'. As shown in FIG. 7b, the radial bore 16 is in alignment with the bore in the hollow shaft, which carries the connection 21. In view thereof, compressed air may pass from the compressed air conduit 12 into the tube of the cable 24 attached to the terminal 21, and then to the terminal 21'. To the contrary, the terminals 19', 20 and 22 as well as 23' are without pressure signal.

From the terminals 19 to 23' pressure fluid passes to feed channels 19a to 23a respectively which are located in the wall of the housing 133". The channel 21a, which with the assumed situation contains a pressure signal, may be seen in FIG. 6. The channel branches into two feed channels 21b and 210, which, like the feed channels 134 and 135 in FIG. 8 discharge into an inside chamber 103 of the housing 133". The feed channels 210 correspond to the feed channels 190, 20c, 22c and 230, while the feed channels 21b correspond to the feed channels 19b, 20b, 22b and 23b.

The feed signal channels l9c-23c or 19b-23b, respectively are accordingly connected pairwise with the signal channels 1911-23 and therefore also with the leads of the cable outflow as well as the pneumatic cable 24. The apertures of all signal channels combined pairwise are correlated offset to the height and the side in reference to the switch element 136" or the central axis of the switch housing 133".

This arrangement measures the theoretical value setter of the construction pendulum switch on the prop 29. In the situation shown, namely the feed channels 210 and 21b determine this theoretical setting of the prop 29. The setting principle of the feed channels 21b and 21c as well as the outlet channels 21d and 21a correspond to the principle of the feed channels 134 and 135 as well as to the outlet channels 138 and 139 of FIG. 8, so that the setting members coupled at the outlet side and the thrust piston drive, which alter the position of the prop 29, need not be shown.

As soon as the switch housing 1 of the guide pendulum switch upon a change in the angle is again rotated about the shaft 10, the bore for example may be aligned with the radial bore which carries the terminal (FIG. 7a). In this way the feed channels 20b and 200 are connected with the pertaining outflow channels 20d or 20s with pressure signals, so that now these pressure outflow channels determine the theoretical position. In this manner the prop 29 rocks until the switch element 136" finds itself in the correct position between the feed and outflow channels according to the principle explained on the basis of FIG. 8. v

All the outflow channels l9d-23d. which correspond to the outflow channels 138, 139 and therefore lead to an amplifier 141a, carry check valves 33a, which close in direction to the chamber 103 of the housing and therewith in direction to the switch element 136'.

The outflow channels 21e, which at the time correspond to the outflow channel 138 in FIG. 8; lead to an amplifier I4-1b and have check valves 33b.

In front of the amplifier 141a or 141b, respectively are connected, however, pressure chambers 32a or 32b, respectively, which evacuate to the outside through bores 34a or 34b.

In this manner the amplifiers" 141a and 14lb are so designated that upon pressure impact of the one amplifier, the compressed air cannot escape from the other amplifier. At the same time, however, after a time determined by the throttling, the amplifiers are relieved of pressure fluid.

The controlling device described in the foregoing starts with the fact that the prop 29 must always be set or positioned perpendicularly to the stratification. To this end through the guide pendulum switch the theoretical value on all construction pendulum switches is adjusted corresponding to the average inclination of the conveyor chutes or troughs. This adjustment takes place automatically, that is, without contact by any attendant personnel, as soon as the conveyor chute or trough has been set at the particular inclination angle a. In view thereof, the props 29 develop in all phases of operation their maximum constructive resistance.

What we claim is: l i

l. A control system for adjusting the angular dispositionof pit props of a traveling mine roof support system comprising a command pendulum-type switch having a rockable housing,}a plumb-bob swingable within said housing for measuring the angle of incidence of the longwall working, and a switching element swinging synchronously with said plumb-bob, actuating means for rocking said switch housing, and means resporisive to movement of said switching element for energizing said actuating means for swinging said housing to a position corresponding to that of said plumb-bob, plumb-bobs on the pit props respectively having synchronously swinging switching elements, and a series of means associated with each of said last switching elements enabling same selectively to cause pressure fluids to emit a signal for correction of the position of the respective prop to a position corresponding to the disposition of said command switch, said last means including a series of ducts leading from and rockable with said switch housing, and a plurality of passages in constant communication with {a pressure fluid source and arranged respectively to register with one of said ducts as determined by the angular position of the switch housing.

2. A control system according to claim 1, characterized by means for fastening said command switch housing to Ta horizontal abutment laid along the floor of the longwall work- 3. A control system according to claim 1, characterized in two signal-associated orifices disposed in rear of said first switching element, a source of pressure fluid maintaining said orifices under pressure, whereby rocking of such switching element uncovers one or the other of said orifices, thereby to activate said actuating means for rocking same in one direction or the other.

4. A control system according to claim 1 in which said actuating means comprises a two-way-acting piston and cylinder assembly.

5. A control system according to claim 1, characterized in that said switch housing comprises a hollow shaft'providetl with several radial bores arranged at intervals in a staggered manner, each bore being in communication with one of said ducts, a rigid pin about which said hollow shaft rocks, supply ing bores in said pin adapted to register with said radial bores respectively, and means for supplying pressure fluid to said supplying bores.

that ducts associated with such pairs of orifices have nonreturn valves adapted automatically to close in the direction of the respective switching element, and ports arranged behind said nonreturn valves open to the atmosphere. 

1. A control system for adjusting the angular disposition of pit props of a traveling mine roof support system comprising a command pendulum-type switch having a rockable housing, a plumbbob swingable within said housing for measuring the angle Of incidence of the longwall working, and a switching element swinging synchronously with said plumb-bob, actuating means for rocking said switch housing, and means responsive to movement of said switching element for energizing said actuating means for swinging said housing to a position corresponding to that of said plumb-bob, plumb-bobs on the pit props respectively having synchronously swinging switching elements, and a series of means associated with each of said last switching elements enabling same selectively to cause pressure fluids to emit a signal for correction of the position of the respective prop to a position corresponding to the disposition of said command switch, said last means including a series of ducts leading from and rockable with said switch housing, and a plurality of passages in constant communication with a pressure fluid source and arranged respectively to register with one of said ducts as determined by the angular position of the switch housing.
 2. A control system according to claim 1, characterized by means for fastening said command switch housing to a horizontal abutment laid along the floor of the longwall working.
 3. A control system according to claim 1, characterized in two signal-associated orifices disposed in rear of said first switching element, a source of pressure fluid maintaining said orifices under pressure, whereby rocking of such switching element uncovers one or the other of said orifices, thereby to activate said actuating means for rocking same in one direction or the other.
 4. A control system according to claim 1 in which said actuating means comprises a two-way-acting piston and cylinder assembly.
 5. A control system according to claim 1, characterized in that said switch housing comprises a hollow shaft provided with several radial bores arranged at intervals in a staggered manner, each bore being in communication with one of said ducts, a rigid pin about which said hollow shaft rocks, supplying bores in said pin adapted to register with said radial bores respectively, and means for supplying pressure fluid to said supplying bores.
 6. A control system as claimed in claim 1, characterized in that said series of means constitute pairs of orifices disposed in rear of the respective switching elements arranged in staggered relation fashion as regards their height and their positions horizontally as to such elements.
 7. A control system as claimed in claim 6, characterized in that ducts associated with such pairs of orifices have nonreturn valves adapted automatically to close in the direction of the respective switching element, and ports arranged behind said nonreturn valves open to the atmosphere. 